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March 1992 Plasticity Evaluation ~ 1 <br />ACZ lac. (ACZ) completed a geotechnical stability analysis of the existing coal refuse pile at the Energy Fuels <br />Coal Inc. (EFCI) Southfield Miae and submitted i[ to the Colorado Mined Land Reclamation Division <br />(CMLRD) oa January 14, 1992. The CMLRD reviewed and approved the analysis, stipulating however, [ha[ <br />EFCI complete sampling and testing of refuse materials to determine material plaz[city, evaluate test results <br />relative [o [he stability analysis, develop a plan to monitor refuse plaztidty, and establish criteria and designs <br />for selective placement of high plasticity reftue if indicated. <br />The following proposed evaluation plan represents the initial step is addressing the CMLRD stipulations. Upon <br />completion of plasticity sampling, testing, evalua[ioq and development of [he monitoring and placement plans <br />and aiteria, all relevant informa[ioq including the 1988 and 1991/1992 stability evaluations will be consolidated, <br />organized and submitted to CMLRD is the form of a technical revision application. <br />1.0 Plasticity Sampling and Testing Plan <br />EFCI proposes to collect and test 8 to 12 refuse samples to determine a representative plaz[city range for [he <br />coal refuse materials previously and currently placed oa the coal refuse stockpile. Samples will be collected <br />from both the existing stockpile and [he preparation plant fine refuse discharge. <br />Approximately 6 to 8 refuse samples will be cotlected from the existing refuse stockpile. EFCI will collect <br />samples from various azeaz of [he pile in order to obtain a good representation of any potential variances in <br />material consistency and characteristics. To the extent possible and is order to avoid redisturbance, samples <br />will be taken from areaz which have not been [opsoiled and reclaimed. If samples are collected in a previously <br />[opsoiled area, special care will be taken [o insure [hat the sample is collected below the topsoil replacement <br />horizon and to avoid mixing topsoil materials with the sample. Approximately one quart samples will be <br />collected at each sampling location and samples will be bagged, labelled and shipped directly to a qualified <br />laboratory for testing. Approximate sample locations will be noted oa a map, site specific conditions, including <br />sampling depth, and variations in refuse material color, composition or consistency, will be noted is a field <br />book, each sample site will be photographed for future reference, and the approximate time period dtuing which <br />the material was placed will be noted if possible. <br />Approximately 2 to 4 refuse samples will be collected from [he preparation plant Fme refuse discharge. The <br />primary purpose in collecting refuse samples duectly from the preparation plant fine refuse discharge is to verify <br />consistency between plasticity test results for raw and in-place samples from the same time period. EFCI is <br />currently in the process of shining production from the west main entries (Jack O'Lan[em Seam) to the south <br />sub-mains (Red Arrow Seam). EFCI plans to obtain plan[ refuse samples both before and after [his transition <br />[o characterize any variances in plaz[city between refuse from [he two coal seams presently being mined. Plant <br />samples will be collected from the fine refuse discharge, bagged, labelled and shipped d'vectly to a qualified <br />laboratory for testing. To [he extent possible, plant samples will be identified relative to the source area(s) for <br />the corresponding coal production run. <br />Atterberg limit tests will be run on all samples to determine liquid limit, plastic limit, and plasticity index. The <br />procedures outlined in American Society for Testing and Materials (ASTM) Standard D-4318 will be utilized <br />for limit testing. <br />Both the plaztic and liquid limit tests utilize material at or sGghdy above natural moisture content, which has <br />been screened to produce a test sample of material pazsing a No. 40 standard sieve. For the liquid limit test, <br />the sample is molded into a flat sample cup and a standardized tool is used [o cut a groove in [he sample. The <br />sample cup is then mounted oa an impact bed which subjects the sample to 25 impact blows by dropping the <br />cup from a specified height onto the faced impact bed. The liquid limit is [he moisture content a[ which the <br />sample deforms with closure a[ [he bottom of the groove under the influence of the repetitive impacts. Sample <br />moisture is adjusted by addition of water or drying and remizutg until the liquid limit is clearly defined, then <br />sample moisture at the limit is determined by standardized methods. <br />\~.k\rn\.°^\riu~ rm <br />o~/io/u] u.,~, <br />